This project seeks to explain the differential socioeconomic adaptation and assimilation of immigrant populations, the children of immigrant populations, and long resident minorities (blacks and Hispanics) in the United States in 1940 and 1950. Subsequent research (to be submitted for funding after the completion of this project) will carry the project forward to 1960, 1970, and 1980. The economic adaptation of immigrant and ethnic minorities is hypothesized to be a product of the characteristics of the minority populations, the opportunities available to them, and societal discrimination. Based upon recently released microdata files from the 1940 and 1950 Population Censuses of the United States, the proposed research will utilize structural equation models to test hypotheses about the determinants of ethnic stratification in the years following the Great Depression and World War II. In addition to standard human capital models and decomposition analysis, the study will draw upon sociological and economic theory regarding the consequences of labor markets for ethnic inequality. Common identification codes for Standard Metropolitan Areas and State Economic Areas in 1940 to 1950 Census Public Use Microdota Files can be used to identify comparable geographical areas and to match them with place characteristics from the City-County Data Book file. The economic attainment of men and women will be separately analyzed and then jointly considered as part of familial units. The methodological and substantive results of this study will speak to research on contemporary processes of immigrant and ethnic socioeconomic attainment.